1. Field of the Invention
The present invention relates to apparatus and methods for endoscopically applying staples individually to body tissue. More particularly, this invention relates to endoscopic surgical staplers for clamping vascular tissue and subsequently driving an individual staple through the tissue and into contact with a staple forming anvil.
2. Description of the Related Art
Surgical apparatus for applying clips to vascular tissue are well known in the art. In these devices, each leg of the clip, typically U-shaped in configuration, is held in one of the opposing jaws of the instrument and the jaws are placed on sides of the vessel. The jaws are then closed to flatten the clip to squeeze the vessel walls together to effect hemostasis. These prior apparatus suffer from the disadvantage that the clip can only be advanced into the jaws of the instrument when the jaws are open so that vessel clamping and clip closing occur simultaneously. Another disadvantage of these clip appliers is they can only be utilized to close a single vessel since they straddle the vessel; they cannot be used to attach approximated vessels or vessel portions.
Instruments for applying single staples one at a time to body tissue are also known. In contrast to clip appliers, these instruments include one jaw which contains a staple and an opposing jaw which has an anvil for deforming the legs of the staple. For example, U.S. Pat. No. 3,278,107 discloses a device where closing of the handles clamps the vessels and forms a single staple. This instrument suffers from the disadvantage associated with the above described clip appliers since clamping of the tissue and application of the staple occur simultaneously.
Some prior art surgical stapling apparatus suffer from the further disadvantage that they require invasive surgical procedures for their use, often causing excessive trauma to the patient and necessitating long post-operative recuperative periods. Invasive surgical procedures also increase the risk of complications such as bleeding, infection, organ damage, nerve damage, blood vessel damage as well as extensive scarring at the surgical site. For these reasons, the use of laparoscopic and endoscopic surgical procedures is increasing in popularity, providing additional incentive to develop the procedures further.
In laparoscopic procedures, surgery is performed in the interior of the abdomen through a small incision; in endoscopic procedures, surgery is performed in any hollow viscus of the body through narrow endoscopic tubes inserted through small entrance wounds in the skin. Laparoscopic and endoscopic procedures generally require that any instrumentation inserted into the body be sealed, i.e., provisions must be made to ensure that gases do not enter or exit the body through the laparoscopic or endoscopic incision as, for example, in surgical procedures in which the surgical region is insufflated to move the tissue layers, e.g. skin, fascia, up and away from the internal body organs. Moreover, laparoscopic and endoscopic procedures often require the surgeon to act on organs, tissues and vessels far removed from the incision, thereby requiring that any instruments used in such procedures be long and narrow while being functionally controllable from the end of the instrument closest to the surgeon, i.e., the proximal end.
Because endoscopic procedures are typically viewed by means of a remote video camera, the need exists for an instrument which allows the user to first clamp tissue, view the clamped area, and decide whether to proceed with staple firing or whether to unclamp and reposition the tissue.
Up to the present there remains a need for an apparatus which is particularly adapted to endoscopically apply staples one at a time to body tissue and in which the user can unclamp and/or reposition the tissue in the engaging jaws before firing a staple. The need also exists for an instrument which, once staple firing has begun, can be withdrawn by the user only after staple formation is complete. Such an instrument could be utilized for closing individual vessels as well as for attaching approximated vessels.